Outgoing U.S. Ambassador to the United Nations Nikki Haley speaks during a meeting with President Donald Trump in the Oval Office of the White House, Tuesday, Oct. 9, 2018, in Washington.(Photo: Evan Vucci, AP)

Trump did not announce a replacement but said it's a great job that people want.

Speaker of the House Paul Ryan and U.S. Sen. Lindsey Graham of South Carolina were among the first politicians to react to the news. Ryan said via Twitter that he is saddened Haley "is leaving the administration but so grateful for her service."

Nikki Haley has been a clear, consistent, and powerful voice for America’s interests and democratic principles on the world stage. She challenged friend and foe to be better. I am saddened that she is leaving the administration, but so grateful for her service. Thank you, Nikki.

Sen. Graham sent a series of tweets complimenting Haley's work as ambassador. He closed by saying "Nikki Haley has a very bright future and will be a key player in both the future of the Republican Party and our nation as a whole for years to come."

She is a clear, concise voice for American leadership, American values, and has been a true agent of reform when it came to the United Nations.

I know all South Carolinians are proud of the service she rendered to our nation and the Trump Administration.

Vice President Mike Pence released a statement of thanks to Haley saying, in part, "Haley served our nation with distinction, faithfully advancing President Trump's America First agenda and she will be missed."

.@nikkihaley has been a tireless leader & supporter of @realDonaldTrump's America First agenda @USUN. She made sure the American people’s voice was heard across the globe, & she did it with poise & strength. Thankful for her leadership. She has made our state & our nation proud!

Jason Hurdich, the sign language interpreter who gained national attention while signing Haley's press conferences during Hurricane Matthew also had a message about Haley's resignation. Hurdich called Haley a fearless leader. "This chapter at the United Nations may end, there’s no doubt she will continue to contribute to our country for time to come," Hurdich said.

@nikkihaley has been a tireless, sensational, and fearless leader yesterday, today, and tomorrow. She embodies American 🇺🇸 values that we all admire. This chapter at the United Nations may end, there’s no doubt she will continue to contribute to our country for time to come.

In a taped news conference from the White House, Haley told reporters the job was the opportunity of a lifetime. She also noted she does not plan to run for President in 2020 and will be supporting President Trump as he seeks re-election.